1. Field of the Invention
The present invention relates a heat transfer member for a heat exchanger, which is obtained by press-forming material to be worked, on the one hand, and a method for manufacturing such a heat transfer member, on the other hand, and especially to the heat transfer member in which a plurality of press-formed portions having a prescribed shape are arranged, on the one hand, and the method for manufacturing same, by which the press-formed portions can be formed on the material to be worked in an appropriate arrangement.
2. Description of the Related Art
If there is a wish that heat transfer coefficient is increased to enhance heat exchange effectiveness, utilizing a heat exchanger by which heat exchange is made between a high temperature fluid and a low temperature fluid, a plate-type exchanger has conventionally been used widely. The plate-type exchanger has a structure in which a plurality of heat transfer members having a plate-shape are placed parallelly one upon another at prescribed intervals so as to form passages, which are separated by means of the respective heat transfer member. A high temperature fluid and a low temperature fluid flow alternately in the above-mentioned passages to make heat exchange through the respective heat transfer members.
Such a heat transfer member, which has patterns of irregularity, is usually formed of a metallic thin sheet. The heat transfer member can be manufactured by a press-forming method utilizing a press-forming device and put into practical use. A set of forming molds has conventionally been used in order to form the heat transfer member. More specifically, a metallic thin sheet serving as material to be worked is placed between the set of molds so that relative movement of the molds form the heat transfer member having a prescribed shape such as a heat transfer face on the metallic sheet.
The conventional heat transfer member having the above-described structure causes a problem of making deformation of the heat transfer member thorough pressure of fluids to bring the adjacent heat transfer members into contact with each other, when the distance between the adjacent heat transfer members is extremely small and there exists a large pressure difference between a high pressure fluid and a low pressure fluid, which flow along the opposite surfaces of the heat transfer member. Such a problem leads to improper change in distance between the adjacent heat transfer members and damage to the heat transfer face, thus causing possibility that effective heat exchange may not be performed.
The heat transfer face of the heat transfer member has a pattern of irregularity with various shapes in order to improve heat transfer effectiveness and condensation property. When the heat transfer face has a non-uniform pattern, in which the pitch of the irregularity becomes small on the one end of the heat transfer face and large on the other end thereof, degree of drawing of material from a non-press formed portion into a press-formed portion in the press formation varies depending upon a position of pattern of irregularity. A remarkable residual distortion exists in the pressed portion and the non-pressed portion of the heat transfer member after completion of the press formation, thus causing problems of warp of a part or entirety of the heat transfer member and deformation thereof.